Special Issue Information

Dear Colleagues,

Creative people like you design novel materials, create wonderful devices, and develop life-changing technologies based on a fascinating science. Growing branches of relevant applied sciences originate from the trunk of the fundamental science, without which this beautiful scientific tree would be a shrub. Novel industrial applications and consumer products add commercial value to the practical outcomes of scientific research.

This Special Issue is devoted to magnetocaloric materials, technologies, and devices with magnetic phase transformations accompanied by the caloric effect. A large magnetocaloric effect is used for energy transformations, in particular, for solid-state cooling and heat pumping, as well as for generating electricity from temperature variations.

A magnetic phase transition in a magnetocaloric material can be caused not only by a change in the applied external magnetic field, but also by a variation of temperature, pressure, stress, strain, or another stimulus. Multicaloric materials exhibit caloric responses to several external stimuli. The multicaloric effect is a combination of more than one effect from a subset of magneto-, electro-, elasto-, and barocaloric effects. While the total number of publications on magnetocaloric materials exceeds the combined number of both electrocaloric and elastocaloric publications, there is a growing number of articles devoted to multicaloric materials and effects.

In this Special Issue, we would like to combine reports on magnetocalorics and related interesting topics, describing scientific discoveries, novel materials, new technologies and devices, theoretical limits, and future anticipations. Some of the topics are listed as the keywords. We welcome theory and experiment, reviews of the current state of the art, and any research related to the magnetocaloric effects, materials, technologies, and devices.

Dr. Nikolai ZarkevichDr. H. YiboleGuest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

(Sc,Ti)Fe2 Laves phases present a relatively unique case of first-order ferro-ferromagnetic transition originating from an instability of the Fe moment. In addition to large magnetoelastic effects making them potential negative thermal expansion materials, here, we show that Sc0.28Ti0.72Fe [...] Read more.

(Sc,Ti)Fe2 Laves phases present a relatively unique case of first-order ferro-ferromagnetic transition originating from an instability of the Fe moment. In addition to large magnetoelastic effects making them potential negative thermal expansion materials, here, we show that Sc0.28Ti0.72Fe2 and related alloys also present sizable magnetocaloric and magnetoresistance effects. Both effects are found substantially larger at the ferro-ferromagnetic transition (Tt1) than near the Curie temperature TC, yet they remain limited in comparison to other classes of giant magnetocaloric materials. We suggest a strategy to improve these properties by bringing the transition at Tt1 close to TC, and test its possible realization by Co or Mn for Fe substitutions. The structural and magnetic phase diagrams of Sc0.28Ti0.72Fe2−xTx alloys with T = Mn or Co are explored. Substitutions for Fe by adjacent Mn or Co elements give rise to a breakdown of the long-range ferromagnetic order, as well as a swift disappearance of finite moment magnetism.
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The magnetic and magnetocaloric effects of potassium-substituted La0.8−xKxBa0.05Sr0.15MnO3 (0 ≤ x ≤ 0.20) manganite were explored. The samples in polycrystalline form were synthesized by the sol–gel method, with a final sintering temperature of
[...] Read more.

The magnetic and magnetocaloric effects of potassium-substituted La0.8−xKxBa0.05Sr0.15MnO3 (0 ≤ x ≤ 0.20) manganite were explored. The samples in polycrystalline form were synthesized by the sol–gel method, with a final sintering temperature of 1100 °C. Powder X-ray diffraction (XRD) patterns refined by Rietveld refinement show that all samples crystallized in rhombohedral structure with R-3c space group. The unit cell volume of the samples decreases with increasing potassium concentration. In addition, small changes in average bond length and bond angle are also observed in the samples. Scanning electron microscope (SEM) images reveal that the largest average grain size was observed for x = 0.10. Field-cooled (FC) magnetization measurements show that the Curie temperature (TC) of the samples increases from 320 K for x = 0 to 360 K for x = 0.2. The largest magnetocaloric (MCE) effect, which is represented by maximum magnetic entropy change (−ΔSM,MAX), reaches its greatest value for the x = 0.10 sample. The monotonous increase in TC suggests that TC is mainly governed by the ferromagnetic coupling between Mn ions induced by the changes on average bond length and bond angle. The obtained −ΔSM,MAX value suggests that MCE property is more sensitive to Zener theory of double exchange, which is strongly related to the Mn3+/Mn4+ ratio of the samples.
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